Connection apparatus for power converter

This application is a Continuation Application of PCT Application No. PCT/JP2010/058057, filed May 12, 2010, the entire contents of which are incorporated herein by reference.

1. Field of the Invention

The present invention relates to a connection apparatus for connecting single-unit power converters.

2. Description of the Related Art

In general, in the field of, for example, solar energy generation, a plurality of single-unit power converters are connected in parallel to provide a power converter of a large capacity.

However, the operation of connecting a plurality of single-unit power converters in parallel requires lots of time and labor in installation and wiring.

It is an object of the invention to provide a connection apparatus capable of easily connecting single-unit power converters.

In accordance with an aspect of the invention, there is provided a connection, apparatus for a power converter apparatus which comprises power converting units with power converting circuits configured to convert direct-current power into alternating-current power, a lead-in board configured to receive alternating-current power output from the power converting units, and frames configured to mount therein the power converting units, comprising: alternating-current output connecting means provided in the respective frames for connecting to output terminals configured to output alternating-current power of the power converting units; cables configured to electrically connect the alternating-current output connecting means in the respective frames to the lead-in board; a parallel circuit formed of the cables connected in parallel; and opening/closing means incorporated, in the lead-in board for opening and closing alternating-current power lines, the alternating-current power lines connecting the power converting units to the parallel circuit.

FIG. 1 is a view illustrating the structure of the main circuit of a power converter apparatus according to a first embodiment of the invention;

FIG. 2 is a view illustrating the structure of a control system circuit for the power converter apparatus of the first embodiment;

FIG. 3 is a view illustrating the structure of a connection apparatus for the power converter apparatus of the first embodiment; and

FIG. 4 is a view illustrating the structure of the main circuit of a power converter apparatus according to a second embodiment of the invention.

Embodiments of the invention will be described with reference to the accompanying drawings.

First Embodiment

FIG. 1 is a view illustrating the structure of the main circuit of a power converter apparatus 10 according to a first embodiment of the invention. FIG. 2 is a view illustrating the structure of a control system circuit for the power converter apparatus 10 of the first embodiment. FIG. 3 is a view illustrating the structure of a connection apparatus 20 for the power converter apparatus 10 of the first embodiment. In these figures, like reference numbers denote like elements, and description will be given mainly of different portions.

The power converter apparatus 10 comprises four power converting units 3 A, 3 B, 3 C and 3 D, and a connection apparatus 20 for the power converting units. The connection apparatus 20 for the power converting units comprises a lead-in board 1 and a connection base 2 .

The lead-in board 1 comprises a circuit formed of the alternating-current (AC) sides of four power converting units 3 A to 3 D connected in parallel. The lead-in board 1 is configured to lead in the AC power of the four power converting units 3 A to 3 D. The AC power output from the four power converting units is synthesized by the parallel-connected circuit. The lead-in board 1 outputs the AC power synthesized by the parallel-connected circuit. The lead-in board 1 supplies the synthesized high AC power to an AC load. Furthermore, the lead-in board 1 supplies the synthesized high AC power to control power sources for the four power converting units 3 A to 3 D and the lead-in board 1 itself.

The connection base 2 is provided for fixing the lead-in board 1 and the four power converting units 3 A to 3 D on the ground. The lead-in board 1 is placed on the connection base 2 . When the four power converting units 3 A to 3 D are placed on the connection base 2 , the main circuits and control circuits of the lead-in board 1 and the power converting units 3 A to 3 D are connected.

The power converting units 3 A to 3 D are machines installed at the connection apparatus 20 for the power converter apparatus. The power converting units 3 A to 3 D are single-unit power converters that can be operated independently, and are, for example, power conditioning Systems (PCS). The direct-current (DC) sides of the power converting units 3 A to 3 D is connected to solar batteries 9 A, 9 B, 9 C and 9 D, respectively. The AC sides of the power converting units 3 A to 3 D is connected to the main circuit of the lead-in board 1 via cables CA, CB, CD and CD, respectively. Further, the power converting units 3 A to 3 D are connected to the lead-in board 1 via local area network (LAN) lines LA to LD.

Referring now to FIG. 1 , the main circuit of the power converter apparatus 10 will be described.

Each of the power converting units 3 A to 3 D comprises a power converter 35 , a DC breaker 36 , a contactor 37 and a control power switch S 3 .

The power converter 35 comprises a power converting circuit for converting the DC power supplied from the solar battery 9 A to 9 D into a three-phase AC current. The power converter 35 outputs the resultant three-phase AC current.

The DC breaker 36 is provided at the DC input side of the power converter 35 . When the DC breaker 36 is closed, the DC power is supplied from the solar battery 9 A to 9 D to the power converter 35 . When the DC breaker 36 is open, no DC power is supplied from the solar battery 9 A to 9 D to the power converter 35 .

The contactor 37 is provided at the AC output side of the power converter 35 . The AC output side of the power converter 35 is connected to the cable CA to CD. When the contactor 37 is closed, AC power is output from the power converter 35 . When the contactor 37 is open, no AC power is output from the power converter 35 .

The control, power switch S 3 is provided to operate the power converting unit 3 A to 3 D and stop the operation of the same.

The lead-in board 1 comprises breakers 13 A, 13 B, 13 C and 13 D, a transformer 15 , an uninterruptible power system (UPS) 16 , and a control power source switch S 1 .

The breakers 13 A to 13 D are connected to the AC output sides of the power converting units 3 A to 3 D via the cables CA to CD, respectively. The output sides of the four breakers 13 A to 13 D are connected in parallel. Accordingly, the AC power output from the four breakers 13 A to 13 D is synthesized.

The synthesized AC power is supplied as the AC output of the power converter apparatus 10 to the AC load and the control power sources of all the power converting units 3 A to 3 D. When the breakers 13 A to 13 D are closed, AC power is output from the power converting units 3 A to 3 D, respectively. When the breakers 13 A to 13 D are open, no AC power is output from the power converting units 3 A to 3 D corresponding to the breakers 13 A to 13 D.

The transformer 15 transforms the synthesized AC power into an AC voltage appropriate for the UPS 16 .

The UPS 16 supplies AC power to the control power sources of the power converting units 3 A to 3 D and the lead-in board 1 , based on the AC power supplied from the transformer 15 .

The control power source switch S 1 is used to operate and stop the lead-in board 1 .

Referring then to FIG. 2 , a description will be given of a control circuit for the power converter apparatus 10 .

Each of the power converting units 3 A to 3 D comprises a display operation unit 31 and a control board 33 .

The display operation unit 31 has an operation function of operating the power converting units 3 A to 3 D, and a display function of displaying information used for, for example, monitoring. The display operation unit 31 performs transmission and reception of information to and from the lead-in board 1 and the power converting units 3 A to 3 D via the LAN lines LA to LD.

More specifically, the operation function is used to operate the corresponding one of the power converting units 3 A to 3 D, also to operate the other power converting units 3 A to 3 D, and to operate each element of the lead-in board 1 .

For instance, each display operation unit 31 opens and closes the DC breakers 36 and contactors 37 of all the power converting units 3 A to 3 D, and operates (e.g., starts the operation, adjusts the operation, and stops the operation) the power converters 35 of all the power converting units 3 A to 3 D. Further, regarding the operations for the lead-in board 1 , each display operation unit 31 opens and closes the breakers 13 A to 13 D. More specifically, each display operation unit 31 performs open/close operations of the corresponding one of the breakers 13 A to 13 D, performs open/close operations of an arbitrary one of the breakers 13 A to 13 D, and simultaneously performs open/close operations of all the breakers 13 A to 13 D.

Further, each display operation unit 31 displays, for example, the open and closed states of the DC breakers 36 and the contactors 37 , and the operation states of the power converters 35 .

Each control board 33 performs processes associated with the control of the power converter apparatus 10 . The control board 33 performs control upon receiving a control instruction, such as an operation control, sent from the display operation unit 31 , the lead-in board 1 , or any other power converting unit 3 A to 3 D for controlling its own power converting unit 3 A to 3 D. In accordance with the operation of the display section 31 , the control board 33 controls the elements of the power converting unit 3 A to 3 D, and outputs a control instruction to the lead-in board 1 or any other power converting unit 3 A to 3 D.

The lead-in board 1 further comprises a display operation unit 11 , a HUB 12 , the aforementioned breakers 13 A to 130 , and an emergency stop button 14 .

The HUB 12 is connected to the display operation units 31 of the power converting units 3 A to 3 D via the LAN lines LA to LD, respectively.

The display operation unit 11 has a function of operating ail elements of the power converter apparatus 10 , and a function of displaying all information associated with the power converter apparatus 10 .

Regarding the operation for the power converting units 3 A to 3 D, the display operation unit 11 has a function equivalent to that of the display operation unit 31 of each power converting unit 3 A to 3 D. The display operation unit 11 operates an arbitrary one of the power converting units 3 A to 3 D, displays an abnormality or an alert, and instructs transmission/reception of information. Regarding the operation for the lead-in board 1 , the display operation unit 11 , for example, opens and closes an arbitrary one of the breakers 13 A to 13 D.

The display operation unit 11 accesses the HUB 12 to acquire the information associated with all the power converting units 3 A to 3 D. Based on the thus-acquired information, the display operation unit 11 displays arbitrary information associated with the power converter apparatus 10 . The display operation unit 11 transmits information to arbitrary one(s) of the power converting units 3 A to 3 D via the HUB 12 .

The display operation unit 11 has a display function of displaying information associated with the power converting units 3 A to 3 D, which function is equivalent to that of the display operation units 31 of the power converting units 3 A to 3 D. The display operation unit 11 displays a current, voltage or power supplied to the load, and displays information associated with, for example, an abnormality state of each element of the power converter apparatus 10 , an alert thereto, and a monitored state thereof.

The emergency stop button 14 is used to urgently stop the operation of the power converter apparatus 10 in an emergency case. When an operator presses the emergency stop button 14 , all breakers 13 A to 13 D, and all DC breakers 36 and contactors 37 of the power converting units 3 A to 3 D, are released. Further, in this case, the power converting operations of the power converters 35 of the power converting units 3 A to 3 D may be stopped.

Referring then to FIG. 3 , a description will be given of the connection apparatus 20 of the power converter apparatus.

The connection apparatus 20 of the power converter apparatus comprises the connection base 2 and the lead-in board 1 attached thereto.

The connection base 2 comprises four frames UA, UB, UC and UD for installing the four power converting units 3 A, 3 B, 3 C and 3 D, respectively. The connection base 2 is formed of, for example, a shaped steel.

The frames UA, UB, UC and UD comprise AC output connection sections 21 A, 21 B, 21 C and 21 D and connectors 22 A, 22 B, 22 C and 22 D, respectively.

The AC output connection, sections 21 A to 21 D are sections to be connected to the AC output terminals of the power converting units 3 A to 3 D. When the AC output terminals of the power converting units 3 A to 3 D are connected to the AC output connection sections 21 A to 21 D, respectively, the U, V and W phases of the three-phase alternating current are connected to the lead-in board 1 via the cables CA, CB, CC and CD. As a result, the main circuit of the power converter apparatus 10 is formed.

The connectors 22 A, 22 B, 22 C and 22 D are connection sections for connecting the LAN lines LA, LB, LC and LD to the power converting units 3 A, 3 B, 3 C and 3 D to transmit information thereto and receives information therefrom. When the power converting units 3 A to 3 D are connected to the connectors 22 A to 22 D via the LAN lines LA to LD, a network for enabling the power converting units 3 A to 3 D to transmit and receive information to and from the lead-in board 1 is formed by the LAN lines LA to LD.

In the first embodiment, the connection apparatus 20 enables the power converter apparatus 10 of a large capacity, which comprises the plurality of single-unit power converting units 3 A to 3 D connected in parallel, to be constructed easily. For instance, when a plurality of existing power converters 3 A to 3 D are installed, the use of the connection apparatus 20 for power converter can shorten the time required to construct the power converter apparatus 10 of a large capacity, which comprises the plurality of single-unit power converting units 3 A to 3 D connected in parallel.

Further, by connecting the plurality of power converting units 3 A to 3 D in parallel by the connection apparatus 20 for power converter, the power converting units 3 A to 3 D can be operated, monitored and managed simultaneously. Furthermore, since the lead-in board 1 and the power converting units 3 A to 3 D are connected by the connection base 2 and the LAN lines LA to LD, information can be interactively transmitted between the lead-in board 1 and the power converting units 3 A to 3 D. As a result, any one of the lead-in board 1 and the power converting units 3 A to 3 D can operate, monitor and manage the entire power converter apparatus 10 .

In addition, the emergency stop button 14 of the lead-in board 1 can easily stop the operation of the power converter apparatus 10 in an emergency case.

Also, since the breakers 13 A to 13 D corresponding to the power converting units 3 A to 3 D are incorporated in the lead-in board 1 , the lead-in board 1 can protect the main circuit.

Moreover, by selectively releasing the breakers 13 A to 13 D, the main circuits can be easily cut, thereby further facilitating the maintenance of the power converter apparatus 10 .

Second Embodiment

FIG. 4 shows the main circuit of a power converter apparatus 10 A according to a second embodiment of the invention.

The power converter apparatus 10 A supplies, to the control power sources of the power converting units 3 A to 3 D and the lead-in board 1 , AG power from an AC power source PW as another system, instead of the AC power based on the solar batteries 9 A to 9 D. The other structure of the second embodiment is similar to that of the first embodiment.

A lead-in board 1 A incorporated in the second embodiment is obtained by removing the transformer 15 and the UPS 16 from the lead-in board 1 of the first embodiment shown in FIG. 1 . A connection base 2 A incorporated in the second embodiment is obtained by modifying the connection base 2 of the first embodiment shown in FIG. 1 to include a line for receiving AC power from the external AC power source PW. The other structure of the second embodiment is similar to that of the first embodiment.

The connection base 2 A applies the AC power from the external AC power source PW to the control power sources of the lead-in board 1 and the four power converting units 3 A to 3 D.

In the power converter apparatus 10 A of the second embodiment, AC power is supplied from the external AC power source PW to the control power sources of the lead-in board 1 and the four power converting units 3 A to 3 D. This structure can provide the same advantage as the first embodiment.

The present invention is not limited to the above-described embodiments, but may be modified in various ways without departing from the scope. Various inventions can be realized by appropriately combining the structural elements disclosed in the embodiments. For instance, some of the disclosed structural elements may be deleted. Some structural elements of different embodiments may be combined appropriately.